Sherman Minton Bridge – Kent Zinn, Michael Baker

Sherman Minton Bridge
P j BBackground
Project
k
d
Metropolitan
Area
Louisville Metropolitan
p
Area

Location
 I-64
over Ohio River
 Link between IN & KY
ridge
Sherman Minton Bridge
g

Structure Information
 Tied
Arch
 2 – 800 foot spans
 Double-deck structure
 Navigable waterway underneath
Inspection
p
Historyy

Initial construction – 1961

NBIS requires 2-year
2 year Inspection Cycle

P i
Previous
Inspection
I
i Yielded
Yi ld d Various
V i
Fi
Findings
di
 Cracks
detected in multiple welds
Wh is
What
i a Ti
Tied
dA
Arch?
h?
What is a Tied Arch?
WEIGHT OF BRIDGE ….. HANGS FROM HANGERS

Think of a bow and arrow….



Stand it on a table like shown
P h down
Push
d
on the
th bow
b
What would happen if we cut the string?
Tie Girder
Tied arches are FRACTURE CRITICAL bridges.
Loss of the tie = likely collapse of the entire span
Web Plate(s)
Flange Plate(s)
Wh Are
What
A Th
The PProblems?
bl
?
Why
y Sherman Minton?

Type of Material
 “T1”
Steel
 VERY
high
g strength
g steel
 Susceptible to FRACTURE at cold temperatures and with
small cracks

Sensitive Details
 Tie
girder welds
 Diaphragm plates
 Lateral bracing details
Tie Girder Welds
176 Individual welds p
per tie x 2 ties x 2 spans
p
= 704 potential
p
fracture sites
Tie Girder Welds
Tie Girder Concerns

…the serious consequences
q
of weld cracking
g associated with the
tie girder of a tied arch structure should not be overlooked.

Fracture Critical Tie Girder

Lack of Internal Redundancy of the welded Tie Girder
Source: 1978 FHWA Technical Advisory
Diaphragm
p g Lugs
g
33 diaphragms
p g per
p tie x 2 ties x 2 spans
p
x 8 lugs
g per
p diaphragm
p g x 2 legs
g = 2112 welds
Diaphragm
Web PPlate
Diaphragm
p g Lugs
g
Flange Plate
Diaphragm lug
Lateral Bracing
g Plates
11 p
panels x 2 plates
p
per
p panel
p
x 2 ties x 2 spans
p
= 88 connection plates
p
Lateral Bracing
g Plates
Fi H d RResponse
First-Hand
Inspection
p
& Testing
g

COMPLETE hands-on visual inspection
p
of EVERY
INCH of weld metal on the tie girder
 What

Nondestructive testing
 What

can we find that we can’t even see?
Extensive sampling of bridge materials
 How

can we find?
strong, how tough, how big of a crack is “too big”?
Current effort
C
ff MOST comprehensive
h i visual,
i l
nondestructive testing and physical testing program,
ever conducted
Hands On Visual Inspection
p
Non-Destructive Testing
g

Performance Testing
of Technicians
Tie Girder Welds

Its what we CAN
CAN’TT see that’s
that s the problem….
•75% of web plate welds
contained “rejectable”
j
indications”
Tie Girder Welds – Past Repairs
p

Use of selected
“coring” repairs
Why
y Even Small Cracks Can Matter
120
60
Assumed / Computed Loading
Safety BBased
on Fractture
Critical Strress, KSI
80
Basic Material Strength
Safeety Based on Sttrength
100
40
20
0
0.00
1.00
2.00
3.00
4.00
Flaw Size, inches
5.00
6.00
7.00
Bridge
g Closed
Retrofit Options
p
Considered

Option #1 Local Plating
 50

/ 100 ksi local plating of joints
Option #2 – Global Plating
 Extension

of Option #1 with extra full length plates
Option #3 – Tie Post Tensioning
 Full
length PT of the tie to fully or partly decompress
the section

Option #4 – Tie Replacement
 Sequential
replacement of the tie in place
3D Model
Local Model Details
PT Deformations x50
Vertical and horizontal deformations approximately 6” each
Global Plating
g Alternate
Local Plating
g Alternate
Tie Replacement
p
Alternate
Comparison
p
Matrix
Working Options Description
Duration in Open to Traffic Estimated Remaining Months
Date
Cost
Service Life
Value
Level of Public Safety
1
Local Plating xx
xx
xx
xx
xx
xx
2
Global Plating
xx
xx
xx
xx
xx
xx
3
Post Tensioning
xx
xx
xx
xx
xx
xx
4
Tie Replacement
xx
xx
xx
xx
xx
xx
5
Superstructure Replacement
xx
xx
xx
xx
xx
xx
6
Bridge Replacement
Bridge Replacement
xx
xx
xx
xx
xx
xx
Discovery & Solution Timeline
Discoveryy & Solution Timeline

Inspection NTP to Intermediate Repair
 3.5

Intermediate Repair to Finding which closed the
bridge
3

weeks
Bridge Closure to Complete NDT work
3

months
weeks
Bridge Closure to Advertisement of Contract
Documents
3
weeks
k
SOLUTION

Sherman Minton Bridge Solution
 Global
plating
Bolt supplemental/alternate
pp
/
tie (plates)
(p
) along
g side both sides
of ties
 Complete redundancy / alternate load path
 $13.8
$13 8 Million
Milli (+/
(+/-))
 4.5 months (+/-)
 Open bids 18 October 2011

High
g Profile
Lessons Learned - Teamwork / Trust
OWNER
CONSULTANT
Procurement & Process
DESIGN
• Expedited Contracts
• Shifting Staff
• Long Hours
• Independent Review
• Aggressive Deadlines
• War Room
CONSTRUCTION
• Design / Bid / Build??
• Procuring Unexpected $$$
• Design Addendums
• Short Advertisements
• Incentives & Disincentives
Thank You